Power

Question 1

What is electrical power?

Answer 1

• Electrical power is the rate electrical energy is transferred each second.

Question 2

What is the MAIN equation for power?

Answer 2

Power = current x voltage

Question 3

Substitute V= IR into the power equatuion…

Give the 2 equations

Answer 3

P = I² x R
P = V²/R

Question 4

What is the power rating of a device?

Answer 4

• How much energy is transferred to device each second.

Question 5

How do I work out the energy transferred of electrical appliance?

Answer 5

P.D x charge flow
Power x time

Question 6

What happens to the power as the current decreases?

Answer 6

The power would decreaseP = I² x R

Question 7

What does the amount of energy an appliance transfers depend on?

Answer 7

• How long the appliance is switched on
• Power of the appliance.

Question 8

Give 2 examples of electrical energy being transferred to kinetic energy of motor in appliance.

Answer 8

• Blender.
• Fan

Question 9

Give an example of electrical energy being transferred to thermal energy in appliance.

Answer 9

• Kettle

Question 10

Give 2 examples of electrical energy being transferred into kinetic energy and thermal energy.

Answer 10

• Hairdryer.
• Washing machine

Question 11

When is work done in a circuit?

Answer 11

• Work is done in a circuit when charge flows.

Question 12

For a fixed resistance, what property should be increased to increase the power developed?

Answer 12

• Increase the current